Synchronous telegraphy.



E.. W'. LARSEN. SYNCHHONOUS TELEGRAPHY.

APPLICTION FILED NOV. 9, 1912.

Patented July 13, 1915.

6 SHEETS-SHEET l.

E. W. -LARSN.

SYNClHRONOUS TELEGRAPHY.

APPucAnon FILED Nov. 9. m2.

Patented July 13, 1915.

6 SHEETS--SHEET 2.

www TQ@ TW. 7 W 7 i MA WM E. W. LARSEN.

SYNCHRONOUS TELEGRAPHY.

APPLICATION FILED Nov.9, 1912.

1,146,581 Patented July 13, 1915.

6 SHEETSSHEET 3.

E. w. LARSEN.

SYNCHRONOUS TELEGRAPHY. APPucAUoN F|L`ED Nov. 9, |912.

l, 146,51 Paf-@med July 13, 1915.

5 SHEETS-SHEET 4.

Afro/waff.

E. W,. LARSEN.

SYNCHRONOUS TELEGRAPHY.

APPLICATION FILED Nov. 9, m2.

1,146,58l Patented July 13, 1915.

6 SHEETS-SHEET 5.

E. W. LARSEN.

SYNGHRONOUS TELEGRAPHY.

AmlcATloN FILED Nov. 9, 1912.

L 14,581 Patented July 13, 1915.

6 SHEETS-SHEET 6.

EXETER V7. L LLRSEN, 0F MNNELPOLIS, l/IlNNESOT.

SYNCHRNGUS TEl'JEG-RAPHY.

Specification of Letters Patent.

Application filed November 9, 191%. Serial No. 730,372.

To all whom t may concern Be it known that li, EINER iii?. LARSEN, citizen ot' the United States, residing liiinneapolis, in the countymf Hennepin and State ot Minnesota, have invented certain new and useful Improvements in Synchronous rl`elegraphy, of which the following is a specification. A

My invention relates to certain improvements in the art of synchronous multiplex telegraphy, and is particularly directed to the attainment of a stable, non-oscillatory system ot synchronism.

The drawings show my method for maintaining such a system in constant equilibrium irrespective or" the number of transmission channels working. No contacts, on. the so-called sunflower, are reserved for the express purpose of correcting the synchronism, but a predetermined number ot impulses is sent into the line per second, every one of which helps to maintain the synchronism, the said impulses being ot any polarity or strength (within working limits). It will be easilyunderstood that a system working on this principle, where the synchronism is as perfect as possible', is extremely iexible, and lends itself to the working of many instruments simultaneously over` a single wire, such as the tansmission of a number of Morse messages or the selection'of the different characters required in printing telegraphy. These impulses sent over the line are fixed in number, and by the modification of these impulses such as changes in polarity or strength, are the dierent instruments operated. 'The synchronism is independent of the number' of such modifications, in contradistinetion to systems allowing only a few such modifications and hence lowering the rate of transmission or the working capacity of the line. The synchronism depends primarily upon the number, and not the character, of impulses sent over the line. Thus, any system relying on alternating current for its synchronism, must necessarily depend upon the rhythm or alternations of the current and hence the integral orn a large number ot modifications ot polarity when transmitting obviously tends to make the synchronism unstable. lln other words, the capacity of the line is lowered.

Referring to the drawings :-Figure l is a top View of one of the motors, part of the sundowers being broken away, Fig. 2 is a view in side eievation ot the motor in Fig. l, showing the motor opened and the trailer disconnected, 3 is a cross section ot the motor, taken on the line .r`ai 3, ot lF ig. l, Fig. i is a top view ot' the speed indicator and governor, 5 is a side elevation ot Fig. i, Fig. (5 is a perspective ot' the magnet shown in Fig. 5,

and also its guides, Fig. i is a cross-section ot' Fig. 5, taken on the line yy, Fig. S is a diagranunatic view ot' the transmitting and receiving instruments at either end of the line, Fig. 9 is a diagrammatic view ot the connections for driving the motors, l0, il and 12 are wiring diagrams et both ends ot the line, showing three dii'erent methods of s vnchronizing, Fig. 13 is a diagrammatic view showing how each transmission channel may be worked on the ordinary quadruple method.

lt mustbe understood that the driving mechanism of both transmitter and receiver may be any motive power such as an ordinary electric or spring motor. The construction followed in the drawings permits a constant normal speed which may be easily changed by the synchronizing impulses.

The motors, one at each end oi" the line, are identical in construction, so that I shall designate by the letter it the one that governs the other and byI the lettel` the other, or the one that is governed or synchronized to the first. rThis notation will assist in understanding the diagrams.

The motor, shown in Figs. l, Q- and 3, is mounted on a suitable base, al, supported by the three feet, a2, as, and it". rThe motor is inelosed by a metal casing consisting of an upper and a lower halt", a5 and a6, respectively. For inspection of the motor, a. and o, may be separated as shown in Fig. 2. a" has five ribs, a7, a8, a, am, and a, intersecting at the center. A soft-iron toothed armature disk, am, rotates horizontally on the spindle, als, the lowerend of which rests on a ball-bearing, a, dropped into a hole at the intersection of the ribs, a7, as, o, am, and au. The upper end of the spindle turns on ball-bearings, a, contained in the ball race, a, which is supported by a spider formed by the crossing of the two strips o and o. rlhe pair of magnets al is supported horizontally on bosses (L20, and the magnet a is supported in the same Way on the bosses of, but diametrically opposite. lhe bosses a2 and Z22 are cast on the lower casing, a6. The

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distance between the pole centers of the magnets, is equal to twice the distance between the armature teeth which swing past the polar projections of the magnets. Into the armature and equidistant from the center, are driven fiber pieces, (L33, equal in number to the armature teeth, A contact arm or brush` r1.3, is mounted on a vertical brass standard, a2, which adapted to rotate on the stud r11". This-stud is fastened to the rib, n.11. b v the screw, (631. and insulated by the fiber rings, a3 and at, as shown in Fig. 3. The position of the arm, (1.24, is varied by means of a thumb nut, Q30, working a worm, (w31. which in turn engages a segment-of a gear, af. which is fastened to the top of the standard, (1.25, and insulated therefrom by the fiber rings, a and (L34. The support or bearing for the thmnb nut a3, and worm (131, is a boss. ai, cast on the lower casing a,

The transmitting and receiving sunflowers rest horizontally on the upper casing a5. The receiver is within the transmitter and consists of a number of metal contacts. (L33, driven into a fiber disk. (L31, equidistant from the center of the motor. IThe transmitting sunflower has the same number of metal contacts, 33. set into the metal ring, a3, and inf sulated therefrom by means of the fiber rings. (13". This ring a1, is insulated from the casing by the fiber ring, a. The transmitting dial. n.33, is fixed in position relative to the casing or framework, but the receiver, n.31, is adapted to rotate within a3, by means of a thumb-nut, (L12. This operates a worm, (11. which engages a segment of a gear, a1*, from which an arln, a, runs to the receiving sunflower. The support or bearing for the thumb screw is a,z boss, a1, cast on the npper casing, a5.

A contact arm or trailer comprising a hub, a, stiff horizontal piece, a, and exible arms, a1, is adapted to be set-screwed on to the upperextremity of the spindle (L13, and to make contact with the contacts of the sunlowers, one extremity for the transmitter and the other for the receiver. The screws, rf', are for the purpose of varying the pressure of the arms.

The binding-posts. am, are used for the magnets, o1, and (131, and are fastened by means of lugs, fr, cast on the lower casing, o, and insulated by the fiber plugs, a. The remaining binding-posts are attached in the same way, but to the upper casing, a, and

are used to make connection with the suniiowers. y

The speed indicator and governor, shown in Figs. 4, 5, G and 7, is mounted on a-suitable base, c. lt consists, essentially. of a magnet, c1, and a metallic reed, 03, adapted to vibrate under the infiuence of the magnet c1. The reed cepis mounted on a casting, 03, and is adapted to be varied with respect to length in the following manner. One end 1s fixed to a piece, c4, which runs in a depression in the casting c3 by means of the screw, c5, which is operated by the thumb-nut. di The reed slides through two pieces (f1 and c3. which are screwed to one end of c3. Hence the rate of vibration of the reed is dependent upon the length from the clamp to its extremity. The reed may then be calibrated and a corresponding scale engraved upon the casting, 03, as shown, the readings being taken from a notch, c, on the slide, 04. The reed, c1, is adapted to make contact with a flexible piece 01, supported by the strip 011 and insulated from it by the fiber block, 013. The screw, 013, is an adjustment for the length of time of contact, and carries a liber tip, 014, for insulation. The strip, 011, follows the horizontal movements of the reed, and hence is screwed to the sam-e block, 0*. and slides through the clamps, c3, and 015. To make the magnet, c1. adjustable. two horizontal rods are employed, 01 and 011, insulated from each other at the supporting ends by alternate pieces of liber, 01S, and c1 and metal, C30 and 031. The magnet is mounted upon a movable carriage comprising two metal blocks, 033, which ride upon the rods. c1 and 011, and a central piece of fiber, 023, for insulation. The lower end of the magnet case is threaded but slides through a vertical hole in 023. Between 023 and the magnet c1, is a large thumb nut, c, which upon being turned, moves the magnet up or down. To move the magnet horizontally, the whole carriage is moved. The. wires from the magnet are connected one to each metal block.

From there the current has A a path through the rods, c1G and c", thence to the pieces c2 andl 021. From there wires are led, one to each of the binding-posts, 035. It will readily be seen that the carriage may be moved to any position without the necessity of carrying any wires, except those from the magnet itself, with it.

Operation: I shall tirst describe the running of one ofthe motors, both being identical. It is driven by a source of electric current such as a battery, 2, Fig. 9, one side of which is connected to one side of the magnet, a, by the wire, 3. The other side of the magnet is connected with the arm',a2, by means of wire 4. From the armature, a, or ground, a wire, 5, passes to the magnet, c1, thence by way of wire 6 to the battery again. The circuit is made and broken by the arm` a, coming alternately into contact with the fiber pieces, o23, and the armature, a. Hence the magnet, a1, is energized at fixed intervals by the battery 2, such intervals coming when an armature tooth is approaching the poles of the magnet. The normal speed of the motor may be varied by turning the thumb-nut, a3", thereby changing the lag or lead of the impulses through the magnet a1. A rotation bration o` of the armature oit course causes a rotation or" the trailer, am. llt must be understood 'that the motor wili operate without the speed indicator' or goyernor whose func will now be described.

The reed is connected by ineansfof wire if to the trailer, a, and the Contact piece, c, is connected to the ground through wires E and 8. By inspection ot these circuits will be seen that a closing of ne contacts the reed and el". will short cic=.iit the fiber pieces. a. lfow the reed c2 in a given position. i tee or natural period ot yiown. which as stated aoore directly from the scale or ci. cl, being in series with the is of course energized the same rate as the magnet, al. and attracts the reed. ci. at intervals depending upon the speed oi" the motor armature. l3nt reed, being loosely coupled, as it were, to the magnet. c1. does not respond to a yery large extent to the latter`s ini'iuence until the number ot' impulses passing through el. is exactly equal to the natural period or' vibration of the reed. V.lhen the reed performs vibrations of large amplitude. according to the well known laws of resonance. This violent vibration ot' the reed closes its contact with cm, which short-circuits the motor contacts and hence tends to slow down its speed. This results in a dying out of the vibration of the reed and the motor tends to accelerate. Finally the motor settles down to a fixed speed where the overlapping of the motor contacts by the governor contacts is just enough to hold the motor to that speed, which is of course governed then by the free vibration ot' the reed. 1t will also be noted that the reading on the scale of c3 corresponds to the number of armature poles passing the magnet am and hence also records the number of contacts passed over by the trailer a4, per unit of time, there being as many transmitting contacts (and of course receiving contacts) as poles on the armature. Ey dispensing with the contact cm the normal speed of the motor may be found by simply turning thc nut c until the reed vibrates in resonance and then taking the reading.

l 1 ig. 8 shows diagrainniaticaily the transmitting and receiving circuits at one end may be read The magnet, drive clrcuit of the line. T he other end is identical with this, so far as these circuits are concerned. it must not be supposed that the nu of ways ot' working this system is limited to the method illustrated in. this diagram. account oi the extreme flexibility of the system innumeralile modes ot working present themselves. `Fig. S shows one of the simpler methods. The source of power is a split battery o and ai, (which might be replaced by electric generators) grounded at its common side at g. Six transn'iitting essi e;

keys., as, are shown, although the number not limited to this. rlhc back stops oi: all the keys are connected to the same side (say positive) of the battery wire il. and the front stops to the. other side hy wire lll. The grounds ot all the six keys are connected to six successive contacts. fr. on the transmitting sunflower through the wiresl 11. rlhere heilig eighteen contacts on thi` Sunflower and only six transmission char:- nels, necessitates every sixth contact being connected together as shown by the wires. 12. The ring. ai, is connected to grounif through a resistance 125 equal to the integral resistance ot' the battery al* or um. 'l`he main line relay 1l, is an ordinary ditierentially wound polar relay. with its split. l5. connected to the trailer. ai" by the wire 115. rll`he main line is represented by l?, and the artificial line by lh. shunted by a condenser. lll. and grounded atl g'. This the ordinary duplex balance, and permits signals being set in both directions on the line sinuiltaneously.

Every sixth contact, a3, on the receiving sunflower, is connected together by wires, 20. Six receiving relays, 2.1, differentially wound, are connected to six successive contacts. ai, a wire QQ, leading from the splits 23. rThe two wires Z-l and 25 leading from the other sides of the relay magnets, are connected, one to each of the contacts 2G and 27 of the -main line relay lil, by means of the wires 2S and 29, respectively. The tongue` 30, of the relay 1-1 is connected through the battery 31, to the splits 15. The current from this battery has two paths depending on which Contact 26 or Q7, the tongue 30 rests. One path is through the wire 1G, one of the contacts am", its corresponding wire Q2, one side of the difierential winding of the relay 21, through wires 2i and 28, thence through the tongue 30 and back to the battery. The other path is the same from the battery to the split Q3, then through wires Q5 and 29 to the 4tongue 30 and back to the battery 31. lhicheyer path. is followed hold the tongues of the relays 3l on a certain side and a reversal of the tongue 30, causes a corresponding reversal of the tongue of 9.1.

The trailer, a, sweeping over the contacts, a, puts each ofthe six keys a. successively in connection with the line 1T. Rotating at a speed of twelve revolutions per second, let us say, puts each key in comuninication with the line thirty-six times per second, which permits of the fastest rate of sending on the keys. All the keys being open as shown, impulses ot only one polarity (from battery aff) are sent into the line at the rate (assuming twelve R. P. S.) of Q16 per second. By the depression of any one of the keys of, the current in the line is reyersed while the trailer a. is crossing over variable y its corresponding contacts on the transmitting sunflower. None of these impulses of course affect the relay 1l, since the current divides at 15, and an equal amount passing through both differential windings of 14 half passing into the real line, 17, to be received at the other end, and half passing through the artificial lline 1S.

The trailer, Z249, (Figs. 10, 11 and 12) at the other end of the line rotates in synchronism with a, which will be explained later. The connection being the same, this trailer, b4, also sends 216 impulses into the line 17 per second (assuming 12 R. P. S.) and each key, Zr, is in communication with the line thirty-six times per second. -These impulses are received on the relay 11 (Fig. S). All the keys @M beiiig open, impulses of one polarity are sent into the line and thus the tongue 30 remains on one side, say contact 27, so that the current from battery 31 has its circuit completed through the side 29, the polarity being such that the armature of the relays 21 are held against their back stops 32. Now suppose a distant key, Z256, to be depressed. Then every time the trailer, Z149, passes over the contacts L38, which correspond to that particular key, the current will be reversed in polarity, which will occur at the rate of thirty-six times per second. Hence the armature or tongue 30 of the relay 14, will cross the gap and make contact with 2G at that same rate, 2'. e. thirty-six times per second. Now since each relay 21 is in communication with the trailer a. thirty-six times per second, this reversal of tongue 30 will cause the current from battery 31 to flow through the trailer, through a certain contact, at, corresponding to the key that is depressed, thence through one leg of the differentialwinding of relay connected to the said Contact, and returning to the battery by way of wire 28, and tongue 30. This, it will be noted, is the opposite leg of the differential winding from what it would be if the tongue had not reversed its position. Hence the tongue of the relay 21, which corresponds to the depressed key, will also reverse and move over to its front contact 33 through which a circuit may be closed to operate any form of receiver such as a sounder or a Morse recorder. Depressing any other key, ZJ, will operate a corresponding relay (and only one)of the group 21, so that each key (also the group 1.56) has a certain corresponding relay and receiver completely at its disposal.

Means for synchronizing the trailers are shown in Figs. 10, 11, 12, and 13. As stated above, the trailer, (L49, sweeping over the contacts, send into the line at twelve .R. P. S., 216 impulses per second. The other `motor is set to run at approximately the same speed normally. Now, these impulses, comng from af", pass through the magnet b21, (Fig. 10) and holds the armature 61"', (and trailer 49 of course) in synchronism with the trailer, a, by retarding or accelerating Z212 according as it is running too fast or too slow. lVhen in synchronism the armature, Zi, presents to the magnet, Z1, as many teeth per unit of time as there are impulses received per unit of time. Hence the trailers, a.49 and Z149, are always in the same angular rotation to one another, andevery contact or key has a definite corresponding contact and receiver. In other words, each ke v has control over its corresponding relay and only that one. Reversals of polarity do not interfere with vthe synchronism since the magnet b21 attracts with any polarity.

Fig. 11 is a modification of Fig. 10. It merely introduces a non-polarized relay 34 into the line, the armature of which closes the circuit 35, 3G and Z121, for the battery 37, for every impulse sent over the line 17. It operates with any polarity and merely relays the feeble line currents into the magnet, b21.

Fig. 12 employs the speed indicator and governor for synchronism. The reed c2 is adjusted by the thumb-nut c, until it vibrates in resonance with the received impulses, and closes the circuit through the contact c1", 3S, 39 and battery 40. Thus its function is the same as that of the relay 3-1 of Fig. 11. The magnet c1 being non-polarized attracts with any polarity.

Fig. 13 shows how each transmission 100 channel may be operated on the ordinary quadruplex scheme. Keys l and 2 operate the pole changer, 3 and -L and keys 5 and 6 operate the current changers 7 and 8. The magnet, b21, is connected in the same way 105 as in Fig. 10, but may be used as in Figs.

11 and 12. It will be understood that the synchronism remains unchanged by any variation of current caused by depressing the key 2. The synchornism depends only upon 110 the number of impulses per second and is absolutely independent of polarity or strength, (within working limits) of the currentl In order to compensate for the lag of 115 transmission, signals caused by capacity,

etc., of the line, the receiving sunflower, (L37,

may be shifted by means of the thumb-nut, a, (or L42) until the best position for receiving is found (Figs. 1, 2 and I claim as my invention:

1. The method of maintaining the synchronous operation of a pair of sunflowers which consists in applying a primary driving power to each sunflower independently 125 of the other, transmitting from one sunflower to the other a. continuous train of impulses of a frequency determined by the rate of rotation of the transmitting sunflower, and utilizing each of said continuous train 13 flower a primary driving power independ' eutly of the transmitting sunflower, transmitting from one sunflower to the other a lcontinuous train of impulses the frequency of' which is determined by the rate rotation of the transmitting sunflower, and

through each impulse transmitted applying to the receiving sunflower a secondary driving power proportional and of a sign corresponding to the diil'erenre between the frequency of the receivingsunflower and the transmitted impulses.

Il. The method of synchronizing a pair of sunflowers which consists in independently applying to each sunflower a primary driving power, continuously governing the application of said primary driving power in response to variations from the desired frequency, transmitting from one sunflower to the other a continuous train of impulses the frequency of which is proportional to the rate of rotation of the transmitting sunflower, and through each transmitted impulse applying to the receiving sunflower a secondary driving power proportional and of .a sign corresponding to the difference lietween the frequency of the receiving sunflower and the frequency of the transmitted impulses.

4L. The .method of maintaining synchronization of a pair of sunflowers which method consists in applying a primary driving power to each motor independently of the other, governing the application of the driv ing primary power of one motor in response to variation from a predetermined standard of frequency independently of the rate of rotation of the other sunflower, transmitting from the other sunflower to the said governed one a continuous train of impulses, and through each impulse applying to said receiving sunflower a secondary driving power proportional and of a sign corresponding to the difference between the frequency of said tra-in of impulses and the frequency of rotation of said receiving sunflower.

5. The method of maintaining the synchronization of a pair of sunflowers which method consists in applying primary driving power to independently of the other, goyerning tl pplication of said primary response to variation from driving power i predeter lined standard independentlyJof the other sunflower, transmitting from the other sunflower to the governed one a continuous train of impulses of a frequency determined hy the transmitting sunflower, and at each impulse applying to said sunflower a secondary driving power pro poi-tional and of a sign rorresponding to the difference loetween the frequency said train of impulses and the 'f equcncy of rotation of the governed sunflower and independently of the aforesaid government of the primary driving power thereof.

(i. rl system of synchronous telegraphy,

comprising a pair of sunflowers, eacn of which is adapted to transmit to the other a continuous train of impulses proportional to the rate of rotation thereof, primary driving motor for each sunflower, local. power connections for each motor, a loca` speed governor for cach motor arranged to regulate the speed according to a predeteri mined standard, and a secondary driving motor for each sunflower deriving its power from the received train of impulses and whose tendency to drive is in one direction or the other according as the frequency of the associated sunflower is greater or less than the frequency of the received impulses.

T. fl system of synchronous.telegraphy, comprising a transmitting and a receiving sunf ower, a primary driving motor for the receiving sunflower, power connections therefor independent of the transmitting sunflower, a speed governor therefor also independent of said transmitting sunflower, a transmitting line between the sunflowers, and a secondary driving motor for said receiving sunflower connected with said transmission line and with said sunflower to tend to drive the same in one direction or the other according as the difference in frequency between the transmitted train of signal impulses and the frequency of rotation of said receiving sunflower is negative or positive.

S. A; system of synchronous telegraphy, comprising transmitting and receiving sunflowers, a primary driving motor for said receiving sunflower independent of the transmitting sunflower, power connections therefor also independent of said transmitting sunflower, a transmission line interconnecting said sunflowers and over which one sunflower may transmit to the other a continuous train of signal impulses, and a secondary driving motor for said receiving sunflower independent ofthe primary driving motor and connected with the said transmission line and said receiving sunflower to tend to drive the same in one direction or another according to whether the diderence between the frequency of the train of impulses and the frequency of rotation of the receiving sunflower is of one or the other.

9. ln a system of synchronous telegraphy,

n: Ut,

a sunflower, a primary driving motor for said sunflower, local power connections therefor, an independently operating secondary driving motor adapted to be controlled by signal impulses and connected to said sunflower to tend to drive the same in one direction or another according as the difference between the frequency of the controlling signal impulses and the frequency of rotation of said sunflower' is of one sign or the other, and means to transmit said signal impulses.

l In a system of synchronous telegraphy, a sunfiower, a toothed armature connected to rotate the same, a primary motor magnet juxtaposed to said armature, a local power circuit for said primary motor magnet, speed governing means in said circuit, a secondary motor magnet also juxtaposed to said armature and arranged in such angular position with respect to the primary motor magnet as to exert a radial draft on the teeth of said armature when energized in synchronism with the primary driving motor, whereby when energized in asynchronism it exerts a tangential driving force in conjunction with or in opposition to the driving force of the primary motor magnet according as the frequency of. its energization is greater or less than the frequency of energization of the primary driving magnet.

11. In a system of synchronous telegraphy, a suniower, an intermittently energized driving motor for the same, the energization of which is controlled from a commutator connected with the sunflower, the connections from the commutator including an angularly adjustable brush by means of the adjustment of which the speed of rotation of the sunflower may be adjusted.

12. In a system of synchronous telegraphy. a sunflower, a toothed armature connected to rotate the same, a primary motor magnet juxtaposed to said armature, a local power circuit for said primary magnet, and a secondary motor-,magnet also juxtaposed to said armature and arranged inl such angular position with respect to the primary motor magnet as to exert a radialV draft on the teeth of said armature when energized in synchronism with the primary driving motor, whereby when energized in asynchronism it exerts a tangential driving force in conjunction with or in opposition to the driving force of the primary motor magnet according as the frequency of its energization is greater or less than the frequency of energization of the primary driving magnet.

In witness whereof, I have hereunto set my hand this 28th day of October 1912. 

